The book "Current Concepts of External Fixation of Fractures", by Uhthoff and Stahl, Springer-Verlag, Berlin Heidelberg N.Y., 1982, pp. 99-102 describes earlier fixtures for osteosynthesis.
The previously known external fixture contains two approximately circular cylindrical steel disks of the same circumference traversed coaxially by a common clamp screw. In the space between both clamping disks a thin friction disk can be provided. A clamping disk of the clamping disk pair has two secantial and cylindrical passages extending parallel to each other for receiving the bridge members (fixture frame rods) which penetrate the radial circular surfaces facing the neighboring clamping disk. Two receiving passages longitudinally slotted over a comparatively large peripheral region thus result, in which the fixture frame rods projecting from one side alongside the longitudinal slots must be pushed in axially.
The cylindrical holder openings for receiving either a bone nail (e.g. a Steinmann nail) or a bone screw (e.g. a Schanze screw) are formed in the previously known fixture analogous to the described cylindrical passages for the fixture frame rods as cylindrical passages longitudinally slotted along one side.
Clamping of a fixture frame rod and a bone screw is effected in the known external fixture therefore jointly by tightening the central clamping screw so that both clamping disks are pressed against each other axially with their circular front surfaces facing and, the peripheral portions of the fixture frame rod and the bone screw protruding from the longitudinal slot of the receiving passages are clamped between them.
The external fixtures described by the book "Current Concepts of External Fixation of Fractures", differs significantly from the earlier fixtures and this device offers the advantage of a simple structure including fewer components, however, this device requires improvement with regard to its handling during operation and the subsequent care of the patient.